Over the past decade, the Five-Factor Model (FFM), initially derived from analyses of trait descriptors in natural languages, has emerged as a useful framework for integrating the bewildering array of personality constructs and scales. Although the FFM dimensions are empirically well-validated across self-reports and ratings by others, little is known about the specific life events, behaviors, and developmental changes associated with them. With the exception of Extraversion and Neuroticism, their genetic bases have not been studied systematically. The cross-situational consistency of behaviors and feelings associated with each factor has not been investigated, and person-centered (and typological) analyses of their intraindividual organization and dynamic interplay are sorely missing. The studies proposed here aim at elaborating these aspects of the FFM. We make use of multiple self and observer assessment instruments widely used in past longitudinal and behavior-genetic studies, including the California Psychological Inventory (CPI), the Adjective Check List (ACL), and the California Adult Q-Sort (CAQ). FFM scales and subscales, scored from these instruments, permit analyses of the FFM in an array of existing data sets. In particular, we propose two collaborative behavior-genetic studies of all five dimensions, reanalyzing CPI and ACL data from (1) a large sample of twins reared together, and (2) a second sample of twins reared apart. We also reexamine three different longitudinal samples, each spanning at least 25 years and including the same self and observer measures. Across the three studies, we will be able to provide replicated findings (1) about changes over time as a function of life events and membership in "person prototypes", and (2) about the long-term stability of individual differences. These analyses will be complemented by a cross-sectional sample of subjects recruited through OMNI Magazine; scores on short FFM scales, as well as basic personal-life data, will be obtained. Finally, a new sample of MBA students will permit studies of cross-situational consistency with behavior codings from videotaped interaction tasks, two audiotaped interviews, and a managerial "in-basket" simulation. Our studies aim to contribute to the basic understanding of personality traits, as measured both by the FFM and by alternative descriptive systems. We emphasize adult personality development and the reciprocal relation between personality and socially relevant life outcomes, such as marital history, parenting, and work achievement.